1. Field of the Invention
This invention relates to an image processing system, and more particularly to an image processing system for move-processing images such as characters or graphics. This invention can be utilized in an image processing device such as a CRT graphic display using raster scanning or an image scanner/printer.
2. Prior Art
Image processing devices such as the CRT graphic displays usually use a so-called bit-mapped pattern memory that stores the dot pattern of two-dimensional image to be displayed or reproduced. The pattern memory has storage locations corresponding to the image to be displayed or reproduced, and reproduces the image by sequentially reading line dot information in synchronization with raster or line scanning of the display or printer. The image processing device often requires the ability to move the image being displayed. The image is moved with or without rotation.
One of the basic methods to move the image is to rewrite the content of the mapped pattern memory, wherein, in the past, rewriting of the dot pattern is usually performed by providing a save memory with storage capacity similar to that of the pattern memory, into which data in the pattern memory is once transferred, and then written again in the pattern memory. Although this method can be applied to any move processing, it has a problem in that it is uneconomical because it requires a save memory with large capacity.
The Japanese Laid-open Patent No. 16485/82 discloses an image display device that is arranged to rotate and move display patterns by changing the timing of pattern memory addressing relative to that of raster scanning. According to this technique, there is an advantage in that the rotation and movement of display pattern can be performed without rewriting the content of pattern memory one by one. However, if different move processing is performed for a plurality of display patterns on the same screen, it is required to separately provide a pattern memory and an address converting circuit for each display pattern, thus requiring a large quantity of hardware.
The Japanese Laid-open Patent No. 135984/82 discloses a display device that divides a pattern memory into small blocks of rows and columns, saves one block of the display pattern in a save memory in rotating the display pattern, moves into this emptied block the block to be moved to this block after the rotation, and causes the display pattern to rotate by repeating the process. Although this technique attains rotation of the display pattern by using a save memory with only a small capacity for one block, it is limited to rotation around the center of the pattern, and cannot be applied to image processing with movement.
In addition, in case where the image processing is performed by program control, a separate program is usually provided for each processing to be performed, for example, for movement without rotation, movement with rotation of 90.degree., movement with rotation of 180.degree., or movement with rotation of 270.degree.. Each program is called according to the processing involved. However, this method makes the amount of programs enormous, and the control complicated. If the program is made common regardless of the contents of processing being performed, such advantages are obtained that the control can be simplified, and the cost can be lowered.